1. Field of the Invention
The present invention relates to a laser soldering apparatus for applying heat to a soldering point by irradiation of a laser light beam, in soldering a component onto a substrate.
2. Description of the Background Art
Japanese Patent Application Publication No. 2004-337894 discloses correcting the spot diameter of a laser light beam at a soldering point by changing a distance between an optics system which irradiates the laser light beam and the soldering point.
FIG. 10 shows a conventional laser soldering apparatus of this kind.
As well as supplying solder 11a from a solder supply unit 11 to a soldering point P on a substrate 6, a light beam 15 is irradiated from a light source 1 onto the soldering point P.
The light beam emitted from the light source 1 is irradiated onto a half-mirror 3 by a first light path 2. The light beam transmitted through the half mirror 3 is irradiated onto the soldering point P on the substrate 6 via optical means 4 which shapes the light beam and collects light onto the substrate 6 and via a protective glass 5.
The light beam reflected at the soldering point P on the substrate 6 passes along a second light path 9 reflected by the half mirror 3, and is then incident on a photoreceptor unit 8 via a mirror 7.
A processing head 16 composed in this way is attached to drive means 10 via first movement means 12. By driving the drive means 10, it is possible to move the processing head 16 to the soldering point P on the substrate 6. The processing head 16 can be moved in the upward/downward direction (Z axis direction) with respect to the substrate 6 by the first movement means 12.
The solder supply unit 11 is attached to the light source 1 via second movement means 13 and third movement means 14. The second movement means 13 can move the solder supply unit 11 in the upward/downward direction (Z axis direction) with respect to the substrate 6. The third movement means 14 moves the solder supply unit 11 horizontally so as to locate a suitable supply position for the solder 11a. 
In the conventional composition, since the light beam is irradiated from a perpendicular direction onto the substrate 6, then if a hole for inserting a component lead or the like is provided on the substrate 6, the laser light leaks out through this hole to the side of a component mounting surface 17 of the substrate 6. Thus, the laser light is irradiated onto the main body of a component disposed on the component mounting surface 17 of the substrate 6, thereby causing damage to the component.
Furthermore, if the laser light passing through the hole is reduced by providing an angle between the normal direction of the substrate 6 and the first light path 2 of the laser light emitted from the light source 1, then it is not possible to observe the base end of the lead portion of the component through the hole.
Moreover, since a distance between the optical means 4 and the substrate 6 is simply changed by the first movement means 12, then the shape of spot of the laser light beam collected on the substrate 6 only undergoes a uniform shape change. Therefore, although it is possible to perform spot soldering, if a plurality of sites are to be soldered consecutively, then the steps of supplying solder and melting the solder by the irradiation of the laser light have to be carried out respectively at processing points, and therefore productivity is low.